ARTICLE: Mechanical Empathy | Preserving the Car While Driving

This is a discussion on ARTICLE: Mechanical Empathy | Preserving the Car While Driving within On owning a car, part of the Team-BHP Advice category; Originally Posted by 100kmph
What's the best was to move an old car (say amby or fiat or pp) up ...

And how do you prevent the car from rolling back while you rev the living daylights out of the engine, before engaging the clutch?

Not quite a great idea as far as the title of this thread goes, is it?

RWD I mean. Pardon. As regards to the part in bold, well. Read the question properly. How does the car climb, after it has halted.

And, I do agree, that this advice is contradictory. But our 1972 1100D, and @100Kmph's 1966 1100D, used to be in very similar shades, until quite recently. Handbrakes missing also! Too much coincidence, don't you opine?

But, contradicting multiple statements is all but common to me, after all, I am just a mere astrophysicist.

You might remember that I wrote this thread. And I am also saying that your suggestion/advice goes against the spirit of this thread.

Handbrake missing in an 1100D/Amby can be rectified without much difficulty by any halfway decent mechanic. A burnt clutch - not so easy.

I also don't want to reduce a car life by any means as far as possible. I never redline even a brand new car which is meant to be revved.
But the mechanic says the handbrake assembly is not available new so I have told him to arrange an used part from the scrapyard. The heel toe method is a bit too difficult for me as the car stalls sometimes. Needs a bit of practice, nah?

It is said that frequent short trips(where even proper operating temperature is not reached) will drastically reduce the life of diesel engines.

Now how is this 'short trip' defined as? In a typical day I do a 13 km in sub-urban traffic from engine start to stop, with the coolant temperature reaching 82-85 C only from the 6th km or so. Not sure whether the engine oil is warmed up to operating temperatures too by that time!?

Now how is this 'short trip' defined as? In a typical day I do a 13 km in sub-urban traffic from engine start to stop, with the coolant temperature reaching 82-85 C only from the 6th km or so. Not sure whether the engine oil is warmed up to operating temperatures too by that time!?

By the 6th km you are at 80+ degree C so that is the operating temperature range, expect the oil also to be in the same temperature range may be a 4-5 degree C less. Not an issue but it is better if your travel has both - bumper-to-bumper traffic and 60+ kmph travel.

Hi all, thanks for this very informative and educational thread. It will be a long while before I can contribute with anything other than a few questions. Here are two that have me somewhat confused (apologies if it has been indirectly answered in this thread, I read all pages but am still not sure)

1. When driving in 4th gear and having to slow down towards a speedbraker or a red signal (say), the practice I presently follow is to depress the clutch, take foot off accelerator, let the car slow down naturally (due to friction) wait to reach the lowest speed desirable (complete stop if red light or 5 kmph if speedbraker) and then downshift to necessary gear (1st/2nd or neutral).

Sometimes (especially if less stressed) I have the practice of shifting to neutral immediately when I realise I will have to slow down / stop and letting the car coast to a halt/slow down. (if speedbraker, as soon as I hit lowest desirable speed I accelerate, cross speedbraker and gear-up again)

Which of the above methods is better?

2. While coming down from heavily jammed flyovers where traffic moves bumper-to-bumper I sometimes switch off the engine and just keep lighting the foot on/off the brake to let the car inch forwards. Is there any adverse effect on the car due to this?

2) When the car is moving in-gear, the engine here is running due to inertia, so under an emergency situation which demands instant throttle input and faster movement of the car, you are on the safer side as one touch to the pedal and your back on power whereas if you depress the clutch pedal or just coast in neutral, you ain't going anywhere.

3) Coasting to the ECU means idle RPM so fuel is supplied to keep the engine running causing loss of FE and waste of energy.

Quote:

Originally Posted by Kumar R

2. While coming down from heavily jammed flyovers where traffic moves bumper-to-bumper I sometimes switch off the engine and just keep lighting the foot on/off the brake to let the car inch forwards. Is there any adverse effect on the car due to this?

Since it is going to be bumper to bumper traffic, let the car be in 1st gear and modulate the sod using the accelerator. All new generation cars have the anti-stall feature which will keep the car going in gear without any throttle input.

Breaks are powered by the engine do if you switch off the engine itself you have NIL braking power and moreover you would have felt a distinct harness in the pedal feel + travel. This happens as the servo motor is not getting power from the engine. Once the engine is restarted, the brake pedal gets free.

If you follow this under emergency situation you'll not have ANY braking power leading to an accident.

We always advocate Engine Braking.
I have been trying to practice it for about 2 months now.

However, it me out when I see the RPM needle shoot up when I upshift to slow down the car.

While I am saving the brake discs from wear and tear, am I not putting a load on the engine, and will it not affect my FE when the RPM needle shoots up ?

Answering to a question which many would ask - what RPM range it shoots.

I am in 5th Gear at 80kmph at 2.2k RPM.
The speed breaker is about 500 mts ahead (I know where the speed breakers are on my route).
I let the RPM come down to 1.8k and then upshift to 4th Gear.
The RPM zooms to about 3k range for 2-3 seconds and then comes down to 1.5, adjusting with the 4th gear rev.

So this 2-3 seconds of 3k range - Isn't it a load on the engine and the FE ?

2) When the car is moving in-gear, the engine here is running due to inertia, so under an emergency situation which demands instant throttle input and faster movement of the car, you are on the safer side as one touch to the pedal and your back on power whereas if you depress the clutch pedal or just coast in neutral, you ain't going anywhere.

3) Coasting to the ECU means idle RPM so fuel is supplied to keep the engine running causing loss of FE and waste of energy.

...

Since it is going to be bumper to bumper traffic, let the car be in 1st gear and modulate the sod using the accelerator. All new generation cars have the anti-stall feature which will keep the car going in gear without any throttle input. Anurag.

Thanks Anurag for taking the trouble to write a reply at 2 am !

I take your point but the doubt I have is whether slowing down while keeping the car in high gear (like 4th) will stall the engine (it will be slowing down from say 50 kmph to 5/10 kmph). When would you suggest I use the clutch and change gear? I drive a Polo 1.2 petrol.

While I am saving the brake discs from wear and tear, am I not putting a load on the engine, and will it not affect my FE when the RPM needle shoots up ?

Good to see the practice put in place to save the brakes. IIRC you drive a Beat D. Right?!

The engines which we drive have been put to much higher stresses and load conditions before they are actually produced for the mass market. Though FE will drop slightly but wear and tear will not be a problem but it depends on the frequency you do this and also the gear:speed relation that witnesses the RPM blip.

Quote:

Originally Posted by Soumyajit9

I am in 5th Gear at 80kmph at 2.2k RPM. I let the RPM come down to 1.8k and then upshift to 4th Gear. The RPM zooms to about 3k range for 2-3 seconds and then comes down to 1.5, adjusting with the 4th gear rev.

I did try the downshift in my Swift ZDi after reading your query.

80kmph @ 5th gear was at 2000 so downshift to 4th gear yob the RPM to 2500 which is fine. When I downshift near 1500 - 1600 RPM, the resultant RPM is near 2100 which is in the peak turbo range anyway.

I advise you to downshift when the RPM drops near 1500, so the resultant RPM will be near 2100 - 2200 which is fine. 3500 - 4000 RPM is harmful but anything near 3000 is fine.

Quote:

Originally Posted by Soumyajit9

So this 2-3 seconds of 3k range - Isn't it a load on the engine and the FE ?

Not alarming at all but it all depends how frequently you do it. Load wise no problem but FE will drop slightly.

Quote:

Originally Posted by Kumar R

I take your point but the doubt I have is whether slowing down while keeping the car in high gear (like 4th) will stall the engine (it will be slowing down from say 50 kmph to 5/10 kmph). When would you suggest I use the clutch and change gear? I drive a Polo 1.2 petrol.

Apologies for not understanding your real question.

Slowing down from 50 kmph to 5 kmph in 4th gear will kill the engine. Every gear has a designated speed in which it will be comfortable to drive on.